In October 2007, Katherine Olson was looking for work. Since graduating summa cum laude from St. Olaf College with a dual degree in theater and Hispanic studies, she had mostly cobbled together part-time jobs  waitressing, teaching Spanish, coaching high school speech.

Olson was looking at nanny listings on Craigslist.org when she came across an ad from a mother who needed someone to look after her 5-year-old daughter. Olson sent an email saying she was interested, and the mother, Amy, agreed to hire her for 10:30 a.m. to 5 p.m. on Thursday the 25th. Amy sent along her address.

A pretty 24-year-old with freckles and tight red curls, Olson wore a pink fleece jacket and spandex stretch pants on the day of the babysitting job. She parked her gold 2003 Hyundai Elantra outside the light teal home in Savage, Minnesota, and walked up the paved driveway.

But when the front door opened, it wasnt Amy who answered. It was a paunchy young man with acne, armed with a Ruger .357-caliber Magnum Blackhawk revolver.

His name was Michael Anderson, and he would soon be dubbed The Craigslist Killer.

When Craig Newmark began sending out emails to his buddies during the winter of 1995, he had no intention of starting a billion-dollar business. A recent transplant to San Francisco whose disarming shyness masked a counterculture streak, Newmark simply wanted to keep fellow computer geeks abreast of local events.

Word spread quickly. During the ensuing months, droves of new members subscribed and began posting their own ads. Newmark made no attempt to moderate, letting the list grow organically. Within a year, Craigs-list had come to resemble more of a digital classifieds section than a mere email list. When Newmark began organizing posts by category, the transition was complete. In 1999, he incorporated the site, making it a for-profit outfit but sticking with the dot-org domain name to reflect its self-described noncommercial nature.

The site experienced exponential growth during the mid-2000s, thanks to word of mouth and its intuitive, no-frills layout. Although Newmark and company wont disclose their financials, estimates conducted by industry observers with the AIM Group suggest that Craigslists revenues skyrocketed from $7 million to $81 million between 2003 and 2008.

Users post more than 40 million new ads per month, according to the sites fact sheet, making it by far the worlds largest source of classified advertising in any medium. The site that once catered exclusively to Newmarks Bay Area pals has established itself in 570 cities in 50 countries and produces upward of 22 billion page views per month.

But its precisely this anything-goes ethic that has politicians and law enforcement officials around the country gunning for Newmarks brainchild. They point to the popular Erotic Services category  intended for legal trades such as phone sex and escorts  as a cesspool of prostitution.

Prostitution is not a victimless crime, says Connecticut Attorney General Richard Blumenthal, who has spearheaded a national campaign to pressure the site to clean up its act. Prostitution ads, pornography, and other promotions of illicit activity can lead to the kind of horrific tragedies weve been seeing.

Hes referring, of course, to the recent spate of headline-grabbing murders that have given us Craigslist Killer as a top Google search term. In February, a Dallas man was found guilty of capital murder for killing a 21-year-old man who responded to his Craigslist ad for a 1995 Chevrolet Caprice. In March, New York City police discovered the body of WABC radio newsman George Weber  hed been stabbed to death, allegedly by a 16-year-old knife fetishist hed solicited via Craigslist. Three weeks later, Boston University medical student Philip Markoff was arrested and accused of murdering a prostitute hed solicited through Craigslist. And just last week, authorities nabbed a man in Kent, Washington, after he allegedly posted a Craigslist ad titled A strange desire, with the intent to solicit a woman to have sex with and then kill.

In South Florida, headlines about Craigs-list thievery are common. In the past year, cops have heard complaints from three Craigslist customers who say they got ripped off over iPhones, with one ending in a scuffle and another a robbery at gunpoint. In April, a Lantana man found his stolen Chevelle on Craigslist; he arranged a meeting, then reported it to the cops after confirming it was his car. In February, police in Palm Beach County arrested a former Delray Beach cop accused of taking part in posting stolen goods on Craigslist.

In an attempt to tamp down the negative headlines, both Newmark and Craigslist CEO Jim Buckmaster have taken to the TV airwaves. Both men were greeted with considerable skepticism. Newmarks April 24 appearance on Nightline came across as less an interview than an ambush, with the balding computer programmer cornered at his desk by interviewer Martin Bashir. Buckmasters interview on CNN that same week was more cordial and nuanced, but he was still on the defensive.

In full damage-control mode, Newmark has become considerably harder to reach, rebuffing the New York Times and the Boston Globe and insisting on seeing interview questions ahead of time.

Which makes it all the more remarkable that this past Sunday, he spoke in public at a memorial concert in Katherine Olsons honor.

Before a throng of cameras, the Olson family stood shoulder to shoulder in front of their home in Cottage Grove, Minnesota, to address the world. Rolf and his son, Karl, bookended mother Nancy and daughter Sarah. It was the day after they received news of Katherines death. Their heads looked heavy as they took questions from the media.

We know where Katherine is, said Nancy. So we are not afraid for Katherine. We will miss her terribly. She was a bright light and free spirit.

Early the next week, a Fed-Ex envelope from San Francisco arrived at Rolfs office at Richfield Lutheran Church, where he serves as a pastor. It was from Craig Newmark. It took him a moment to realize it was the Craig from Craigslist.

Nothing fancy, just a sheet of paper with his handwritten message with his sincere condolence, Rolf recalls. And he said, Please contact me if you want to talk further. Heres my email, heres my phone number; Im available anytime. 

A few days later, after Katherines memorial, Rolf sent Newmark an email thanking him for the letter. And while I was still sitting in the office, I got an email back from him. I mean, it was like ping-ping. Again, he said, If there is anything we can do to support your efforts, dont hesitate to contact me. 

Throughout the ordeal, family members took walks around their neighborhood to think. It was during these talks that they came up with the idea for a memorial concert in Katherines honor. We thought, Wouldnt it be a cool idea?  recalls Nancy.

Rolf spent hours crafting his next message to Newmarks company. So I sent an email off to Jim Buckmaster, their CEO, and was hoping I was very clear with purposes for the concert and what my costs were and asked would they care to donate, says Rolf.

Buckmaster wrote back a message in all lowercase letters: sure. sounds great let us know what you need.

It was so informal, remembers Sarah, Katherines older sister. And thats how they are. Its like a brief text you would send to your friend.

One year after Katherines death, the Olson family flew to New York to appear on the Today Show. On camera, host Meredith Vieira asked Rolf why they chose to finally talk to the media. He answered, One of our philosophies that weve operated with since Katherine died is we want to leverage as much good as we can out of this wretched experience. So today, were here to talk about Katherine, to let her legacy live and have her be defined by her life and not by her death.

It was a day of joy, but the trial of Katherines killer would sour things. Michael John Andersons attorney claimed that his client lured Katherine to the home in Savage for sex and not, as prosecutors put forth, with the intention to kill.

Before the trial, Craigslist had helped law enforcement by assembling a 127-page dossier on Andersons use of the website. The company also dispatched customer-service manager Clint Powell to take the stand. Powell told the courtroom how Anderson first used Craigslist as a way to find ice-fishing gear, truck parts, and collectible plates with misspelled words like Star Terk. This pattern changed in October, as Anderson started trolling for women. Powell read various postings made by Anderson. One said, looks and size dont mean a lot to me. Im not little man, but Im not huge either. Another read, Looking for fresh faces for a new video and Web site new talent only. Also need 18 plus virgin willing to be in a video.

It took five hours for the jury to return its verdict: Anderson was guilty of first- and second-degree murder as well as second-degree manslaughter, charges that carry a mandatory term of life in prison without parole.

Back in Cottage Grove, Rolf and Nancy say they hold no blame for Craigslist. There are evil people out there, says Sarah. And unfortunately, Craigslist is built for everyday people. And so someone that has ill will, someone psychotic, like Michael Anderson or this medical student, they are going to take it for what it is worth. Its a free tool, and evil people will take advantage of whatever they can.

In early November 2007, a month after Katherine Olsons murder, Connecticut Attorney General Richard Blumenthal received a letter from an irate mother. The mother of two teenagers demanded that something be done to help her censor sites like MySpace and Craigslist. Those sites, she wrote, do not only make this task difficult, but virtually impossible.

Most attorneys general might have relegated the missive to the recycling bin. But Blumenthal has been a gritty, ambitious fixture of the Connecticut Democratic Party for decades. He has taken on various crusades with a zeal that ingratiated him to law-and-order types and progressives alike. He banned ATM fees, sued Microsoft and Big Tobacco, and orchestrated a national campaign against misleading sweepstakes mailings. His enthusiasm for courting the national spotlight has brought occasional criticism for attention-seeking, but the tanned 63-year-old is laying the groundwork for a 2012 Senate run.

Rather than disregard the unassuming two-page letter from the mother, Blumenthal found a new cause at which to throw himself with characteristic vigor. The first thing he did was fax Craigslist a short missive. I am certainly concerned that children may have access to such explicit material, he wrote. I would appreciate your review and response to the complaint, as well as any suggestions for improvement.

An attorney for Craigslist, Barry Reingold, replied with a four-page letter that made clear that Craigslist was sympathetic to the womans desire to protect her children from personal advertisements that are intended for adult eyes only. But, Reingold wrote, it was essentially out of their hands. He suggested that she install a web content filter.

Over the course of the next several months, both factions bantered back and forth via conference calls, with Craigslist executives gradually growing more receptive to making some concessions. In early 2008, Newmark and Buckmaster agreed to amp up their enforcement of the sites terms of use and introduced a telephone verification requirement. As a result, the number of posts for erotic services in Hartford, Connecticut, dropped from about 400 per day to 50.

But when a Connecticut woman was arrested March 19, 2008, for prostituting herself on Craigslist, Blumenthal jumped back on the case, livid that sex-worker ads were still polluting the site. He wrote the company again: Craigslist must determine now what type of site it is. If its truly concerned about the issue, it must devote resources and technology to eliminate these postings from its site. Frustrated by what he perceived to be stonewalling, Blumenthal went to the media, accusing Craigslist of profiting from prostitution.

Baffled, Craigslist brass went on the defensive and fired back on the sites blog. We were disappointed that he chose to ignore our recent progress in dramatically improving compliance with our terms of use, shocked at the bizarre assertion that we are stonewalling, and frankly stunned to hear Craigslist recklessly slandered as profiting from prostitution,  wrote Buckmaster. Craigslist will not be used as a punching bag for false and defamatory statements.

In July 2008, the sides arranged their first meeting. Buckmaster, along with two Craigslist attorneys, made the cross-country trek to Rye, New York, just beyond the Connecticut border. They met Blumenthal and a few of his subordinates in a coffee shop and, over the course of a few hours, hashed out an agreement.

Under the accord, Craigslist began charging erotic-services advertisers $5 to $10 per ad, enabling the company to confirm users identities with their credit cards. Craigslist also vowed to donate profits from the sex category to charity.

The agreement was made public in November. Forty attorneys general endorsed the deal, including those from Tennessee, Washington, Colorado, and Arizona. Florida Attorney General Bill McCollum has refused. Asked why, McCollum spokeswoman Sandi Copes sent New Times this email: At the time, we did not feel we had enough information about certain aspects of the settlement and were reluctant to support some of the agreements provisions. Im afraid thats as specific as I can be. Copes declined to elaborate.

Craigslists Buckmaster says the company is doing its best to comply with the attorneys generals concerns.

There are far more  and far more graphic  images on all of the general-purpose internet portals and general-purpose search engines than anyone is ever going to find on Craigslist, says Buckmaster. That said, we arent comfortable with any pornographic images being posted on Craigslist, and were committed to eliminating that.

On an unseasonably snowy March 20 in New York City, George Weber  a passionate, affable 47-year-old radio newsman for WABC  posted a Craigslist ad looking for rough sex.

His solicitation was answered promptly by 16-year-old John Katehis, a self-described sadomasochist Satanist from Queens. I can smother somebody for $60, he wrote to Weber.

The two met in Brooklyn and made their way to Webers first-floor brownstone. There, Katehis allegedly stabbed Weber some 50 times in the neck and torso. When police arrested Katehis at a friends house in upstate New York, he was still wearing clothes he had taken from Webers apartment.

About three weeks later, on April 14, Philip Markoff  a tall, blond, 22-year-old med student at Boston University  came across an erotic-services ad on Craigslist posted by 26-year-old Bronx-based call girl Julissa Brisman. The two arranged a soirée at the Marriott Copley Hotel in Bostons upscale Back Bay district. Seconds after entering the room, Markoff allegedly pounced on Brisman, who, according to a medical examiner, fought back tenaciously. Markoff stands accused of killing Brisman by shooting her three times, twice in the torso, once in the hip.

Markoff was with his fiancée, on their way to Foxwoods Casino in Connecticut, when police pulled him over and arrested him just south of Boston on I-95. The summa cum laude graduate of the State University of New York-Albany was later implicated in a Boston robbery as well as one in Warwick, Rhode Island. A common thread ran through all three crimes: young women solicited through Craigslists erotic-services category.

Even more than the Weber slaying, the Brisman killing captured the public imagination. How could somebody like Markoff  clean-cut, well-educated, ambitious, and in the midst of planning a beachside wedding this summer  do such a thing? The national media dubbed Markoff the Craigslist Killer, a phrase that still makes Newmark and Buckmaster cringe.

Were taken aback any time we hear that term used, says Buckmaster. Although, if you stop and think about it, its a testament to how exceedingly rare violent crime is on Craigslist, when you consider that its the most common way that Americans are meeting each other these days by a significant margin. The reason they dont call him the Handgun Killer or the Boston Killer or the Hotel Killer is because thousands of homicides have involved those factors.

The Weber and Brisman murders couldnt have come at a worse time for Craigslist. Just as the crimes were splashing into prime-time news segments, a sheriff in Chicago was mounting a campaign against the company. Cook County Sheriff Tom Dart filed a federal lawsuit against the site, accusing it of facilitating prostitution. He claims that, during the past two years, his department has arrested more than 200 Craigslist users on charges ranging from prostitution to juvenile pimping and human trafficking.

In the hundreds of arrests that weve made, never have we had one where we went under the guise that its a massage and it turned out that it was just a massage, says Dart. We know whats going on.

Despite Darts confident tone, most legal experts believe his lawsuit has little chance of success  a clause in the federal Communications Decency Act immunizes websites from liability for content posted by third parties.

A far more imposing threat to Craigslist is Connecticuts Blumenthal, who resurfaced in an April 22 open letter with additional, more sweeping demands. We felt the first agreement was a good first step but insufficient, says Blumenthal. The prostitution ads have continued; the pornography is still there. It has failed to accomplish all that wed hoped. Blumenthal implored Craigslist to, among other things, disallow salacious prostitution-themed search terms, hire staff to monitor for pornographic images and ads, and eliminate the erotic-services category.

Buckmaster says Craigslist welcomes the constructive criticism and confirms that the two sides are in the midst of hashing out a voluntary agreement. But dont expect Craigslists most popular and controversial category to go away anytime soon. We added the erotic-services category some years ago at the request of users who had been seeing those ads posted throughout our personals and services categories and wanted to see them collected in one space and put behind a warning screen, says Buckmaster. And having them in one place has allowed them to be monitored more closely, by both our staff and law enforcement.

Others in the online classified trade back Buckmasters assessment. Carl Ferrer, cofounder of Backpage.com, the online classified partner of New Times owner Village Voice Media, points out that even if Blumenthals demands were met, they wouldnt safeguard against people posting elsewhere.

If you eliminate erotic services, the content will just migrate to miscellaneous services and other categories, Ferrer says. Then it becomes a whack-a-mole strategy.

Theres also no evidence that overall rates of prostitution or murder have increased in correlation with Craigslists ascension, says Zollman, of the AIM Group. There have always been hookers. There have always been people who sell drugs and other illegal things. But to call these Craigslist-related crimes is no fairer than calling car accidents GM-related deaths. 

On a cloudless afternoon last Sunday, May 3, about 700 of Katherine Olsons friends and family gathered at Grace Church, a colossal house of worship in Eden Prairie, Minnesota. The last time this group had been together was at Katherines funeral, but those gathered on this day eschewed black clothing in favor of pastel-colored spring attire. There were no tears among the congregants, no Kleenexes hastily passed. This was to be a day of celebration.

When it came time to begin, five members of the Olson family took the stage to subdued applause. Trailing behind in a black suit worn over a tieless maroon dress shirt was Craig Newmark. After a brief introduction by Sarah, Newmark approached the podium, grabbed the microphone, and leaned over his prepared remarks.

I am really, really humbled and really honored to have been invited here today to speak at this tribute to Katherine, extended by the whole Olson family, Newmark told the crowd. I was personally sickened and horrified when I heard about this tragedy. I started Craigslist around 14 years ago as a way to give back to the community.

Rolf stood behind Newmark, gazing thoughtfully at the crowd.

Despite the billions of times well-meaning people have helped each other through Craigslist, it has been devastating to see that it can also be used by bad people to take cruel advantage of others and bring a senseless end to a beautiful young life, Newmark continued. The most recent crime in Boston has been a grim reminder of that.

It became clear he wasnt speaking just on behalf of Katherine but also on behalf of reason and personal responsibility in the age of the internet.

Im saddened that we met under these circumstances, but I am truly inspired by the Olson family, and I extend my love and friendship to them, Newmark concluded. And I applaud everyones effort to let Katherines light continue to shine.